Soil working devices are known from prior art which comprise at least one machine frame, a drive and at least one support arm adapted to be moved up and down by the drive and pivotably supported at the machine frame. The soil working devices further comprise at least one insertion tool adapted to be pivoted about a first pivot axis relative to the support arm and to be moved upward and downward by means of the support arm, the insertion tool being adapted to be inserted into the soil and be pulled out from the same. Prior to insertion into the soil, the insertion tool is in a initial position under a predetermined insertion angle and, due to the movement of the machine frame in the traveling direction, performs a pivot movement in the soil about a first pivot axis in the direction of a first pivoting direction, the pivot movement superposing the upward and downward movement. Further, the soil working device comprises at least one returning means that is coupled to the insertion tool at a first end and is coupled to the returning means at the second end, wherein the returning means, after the insertion tool has left the soil, returns the insertion tool to the initial position by pivoting the insertion tool in a second pivoting direction opposite to the first pivoting direction.
From European Patent Publication EP-A-0037595 a soil working device is known that has two carrying arms guided in a parallelogram-like manner and pivotably supporting a tool holder at one end, while the other end of the arms is pivotably supported at a machine frame. A pushrod of a crank drive is hinged to the tool holder and drives the same so that it performs an up and down movement. One of the two support arms is variable in length and comprises a stop spring means. As soon as the insertion tool is outside the soil, the support arm is pulled to the stop by the spring force. With the insertion tool inserted and the soil working device moving forward, the tool with the tool holder pivots against the traveling direction and the length-variable support arm is extended against the spring force.
However, the previously known soil working devices have the drawback that the insertion tools may be damaged when they hit a hard object in the soil, such as a stone, for example. Further, there is a need for the manufacture of machines that are as light-weight as possible.